Kissing’s Ancient Roots: Study Traces Practice Back 21 Million Years to Human-Ape Ancestor
A new study suggests that kissing, as we know it, isn’t a modern invention – but rather a deeply ingrained behavior inherited from our ancient primate ancestors. Researchers at the University of Oxford have traced the origins of mouth-to-mouth contact back 21 million years, to the common ancestor of humans and great apes.
The groundbreaking research, published in the journal Evolution and Human Behaviour and reported on Wednesday by the France-Presse (AFP) news agency, marks the first comprehensive investigation into the evolutionary history of kissing. The team began by defining kissing as “non-aggressive mouth-to-mouth contact that does not involve the transfer of food,” a crucial distinction for understanding the behavior’s origins.
To understand how this behavior evolved, researchers analyzed data from primate species known to engage in kissing, including chimpanzees, bonobos, and orangutans. They then utilized a primate phylogenetic tree and statistical modeling to estimate the likelihood that earlier ancestors also practiced this intimate behavior.
The study’s conclusion is striking: kissing is an “ancestral behavioral trait in great apes” that emerged between 16.9 and 21.5 million years ago. “The kiss persisted throughout evolution and continues to be present in most great apes,” a press release detailing the study revealed.
“By integrating evolutionary biology with behavioral data, we are able to draw informed conclusions about behavioral traits that do not fossilize, such as kissing,” explained Stuart West, a co-author and professor of evolutionary biology at Oxford. This approach allows scientists to explore behaviors that leave no physical trace in the fossil record.
Matilda Brindle, the study’s principal investigator and a biologist, added that the findings “contribute to a growing body of research that highlights the remarkable diversity of sexual behaviors observed in our primate cousins.”
Perhaps even more surprisingly, the research suggests that our extinct relatives, the Neanderthals, also engaged in kissing. Scientists discovered that Neanderthals, who inhabited Eurasia until approximately 40,000 years ago and coexisted with Homo sapiens, “they probably also practiced kissing.”
This conclusion is bolstered by previous research demonstrating that humans and Neanderthals shared oral microbes (through saliva transfer) and even genetic material (through interbreeding). “This discovery, combined with previous studies…strongly suggests that humans and Neanderthals kissed,” the university emphasized. This paints a picture of a shared intimacy between our species and our ancient cousins, extending beyond mere survival and into the realm of social and perhaps even emotional connection.
